It is known to use tank vent filters in order to clean the supply air flowing into the tank, particularly to dehumidify the air flowing into the tank and to filter particles out. Such tank vent filters are known, for example, from US 2007/0175524 A1, US 2010/0224069 A1 and US 2003/0145728 A1.
A tank vent filter is known from U.S. Pat. No. 2,603,308 that has, on its air outlet side, a chamber that is bordered by two plates with small through recesses in order to prevent contamination of a filter element in the tank vent filter as a result of fuel “sloshing” out of the tank.
Moreover, EP 2 607 136 A1 discloses a tank vent filter having a mechanically actuatable slosh protection device for preventing contamination of the tank vent filter with fuel.
Such a contamination of the tank vent filter with liquid stored in the tank is a concern particularly in mobile applications, for example in motor vehicles, and when the tank is full. The “sloshing-out” of the contents of the tank into the tank vent filter is referred to as so-called “backwash.” The contamination of tank vent filters is particularly grave if the tank is filled at least partially with a urea solution.
To prevent such backwashing, KR 2006 0021582 A contains the teaching of providing a tank vent valve with a sphere that seals the outlet of the tank vent valve when the contents of the tank spill into the valve.
Furthermore, WO 2005/017340 A1 discloses a tank vent filter with a collecting space in the region of the air inlet, the collecting space being sealed with an adapter that opens automatically when a lot of the contents of the tank as collected in the collecting space.
Finally, a tank vent filter is known from WO 2013/066217 A1 that has a filter element that is protected by a cover from any fuel that might penetrate into the tank vent filter. However, such a cover occupies a relatively large amount of space.